Fluid heat exchange apparatus



L. KOQISTRA FLUID HEAT EXCHANGE APPARATUS Aug. 1, 1939.

Filed May 19, 1937 I Lamberi @oisfra Patented Aug. 1, 1939 UNITED STATES PATENT OFFICE FLUID HEAT EXCHANGE APPARATUS Application May 19, 1937, Serial No. 143,437

3 Claims. (Cl. 122-303) My invention relates to water tube boilers and it is particularly concerned with a novel relationship of the horizontal circulators to the other components of a cross drum water tube boiler of the B. & W. type.

Water tube boilers of the type with which my invention is concerned have a bank of horizontally inclined tubes connected at their opposite ends to vertically arranged headers. These components operate as parts of a natural circulation system which includes two sets of circulators between a steam and water separator and opposite sets of headers. The circulators of one set extend from the water space of the separator to the headers at the lower ends of the tubes of said bank. The purpose of these circulators is to supply water to the bank of tubes, and the headers connected to the circulators are usually referred to as downtake headers. The uptake headers, at the opposite ends of the bank of tubes have the circulators of the other set extending upwardly therefrom and thence horizontally to the separator for the purpose of directing the mixture of steam and water to the separator.

Steam is generated in the bank of horizontally inclined tubes and it is important that there be an unfailing and adequate circulation through these tubes during operation of the boiler. Such circulation is difiicult to maintain in such a boiler at high steam pressures, and it has been suggested that adequate circulation might be attained at such pressures by increasing the height of the boiler so that there would be a circulation producing diiferential in the hydraulic heads between the downtake and uptake circulators.

It is not always feasible to follow the above suggestion as to promoting adequate circulation through the steam generating tubes, and, in such cases, this invention provides means which effects adequate circulation where limitations such as installation costs and space factors may preclude recourse to the high head type of boiler. This invention involves the promotion of improved circulation through the steam generating tubes by a different method. It contemplates an increase in circulatory force by reduction in the resistance to the escape of the mixture of steam and water from the upper ends of the steam generating tubes to the headers and through the horizontal circulators to the steam and water drum.

Other objects of the invention will appear as the accompanying description proceeds, the invention being described with reference to the accompanying drawing, in which:

Fig. 1 is a view in the nature of a vertical section through a water tube boiler arranged to illustrate the invention. 6

Fig. 2 is an enlarged view of the upper part of the installation shown in Fig. 1. This figure is in the nature of a vertical section showing the arrangement of the horizontal circulators and the relation of the other parts of the boiler' thereto.

Fig. 3 is a View in the nature of a vertical section taken upon the section line 33 of Fig. 2.

Fig. 4 is a detailed view in the nature of a vertical section, particularly showing the con- 15 struction of one of the uptake headers of the illustrative boiler.

Fig. 1 of the drawing indicates a multiple bank boiler having an upper bank In of horizontally inclined steam generating tubes superposed with 20 reference to a lower bank H of similar tubes. The steam generating tubes extend across the path of the furnace gases passing from the furnace l4 and they are supplied with water at the lower end through the intermediacy of sets of downtake headers I6 and I8 connected to the water space of the drum 20 by the water circulators 22 and the downtake nipples 24.

At the upper ends of the banks of steam generating tubes there are, respectively, upper and lower sets 26 and 28 of uptake headers. The headers of these sets are connected by the uptake nipples 30, and steam and water flows from the uptake headers to the drum 20 through upper circulators 32 and 34 rising from the top 35 ends of the uptake headers 26. These circulators are indicated in a single row arrangement near the headers 26, but their horizontal portions are preferably arranged in two vertically spaced horizontal rows in order to provide sufiicient ligament strength between the tube seats provided in the drum for the connection of these circulators thereto. In addition to the above indicated circulators, I provide other circulators 36 extending from the sides of the uptake headers above the top row of tubes of the bank l0 and ending at the side of the drum opposite the side having the tube seats for the circulators 32 and 34. The additional circulators 36 are also divided into two rows in order to provide adequate ligament strength in the zone of the tube seats.

The additional set of circulators 36 doubles the circulator flow capacity for steam and water, and substantially quarters the flow resistance, for a given hourly quantity. This arrangement of elements therefore results in an increased circulation rate which keeps the tubes of the top row of the bank I0 wet in spite of increase in steaming rates over and above values which had been previously within safe limits, in prior boilers of this type.

The additional circulators 36 pass between the upper portions of the water circulators 22, and under the drum 20. As shown, the water circulators 22 are bent at their upper ends so as to enter the drum in two circumferentially spaced rows. This construction also provides adequate space for the arrangement of the circulators 36. It, furthermore, provides ample metal between adjacent tube seats in the drum 2! The additional circulators 36 are swept by hot gases that have left the tubes of the top row of the bank I0, and, consequently, steam pockets must be prevented in order to avoid local overheating and damage which might be as serious as that at the upper ends of the tubes of the top row for which the additional circulators are provided as a remedy. To avoid the occurrence of such steam pockets the additional circulators 35 are arranged so that they present no downwardly inclined parts, passing from the uptake headers to the drum. All parts of these circulators are level, or rise in level in the direction of fiow. To permit such conditions at the header ends of the circulators 36, the header tube seats for these additional circulator tubes cannot be parallel to the tube seats for the steam generating tubes of the bank Ill because the axes of the latter are inclined downwardly to receive the upper portions of the downwardly inclined tubes. I therefore provide uptake headers 25 which are particularly constructed at their upper ends in the manner indicated in Fig. 4 of the drawing. In this figure the header is shown as having a downwardly presented tube seat all for one of the tubes of the top row of the bank i9 and an upwardly facing tube seat 42 for connection of the additional circulators with the headers. This arrangement permits the first sections of the circulators 36 to be inclined upwardly. As shown in the drawing, the remaining portions of these circulators, up to the bends 64 beyond the water circulators 22, are arranged horizontally, but they may desirably, in some boilers, have slight upward inclinations.

Appurtenant parts of the installation indicated in Fig. 1 of the drawing include the boiler setting framework 50, the burners 54, the water walls 56 and 58, and the interdeck superheater 60. The latter is located in the first gas pass defined, on one side, by the headers 26 and 28, and, on the opposite side, by the baffle 62. A second gas pass is provided by the baflles 64 and 62, and the furnace gases pass from the second gas pass into the third gas pass 66, and thence to the fiue 68.

Although I have described my invention with reference to the particular structures illustrated in the drawing, it is to be understood that it is not limited to all of the details thereof, but that it may be employed in such combinations as are within the scope of the subjoined claims The invention is not limited to the particular number of rows of horizontal circulators indicated herein. Alternate circulators in one row may communicate with the downtake side of the drum and the remaining circulators communicate with the opposite side of the drum, thereby improving the ligament strength of the uptake side of the drum, and also improving water level conditions.

Having described my invention in the manner prescribed by law, and particularly see. 4888 of the Revised Statutes, I claim:

1. In a water tube steam boiler, a steam and water separator, uptake headers, downtake headers, horizontally inclined steam generating tubes connecting the uptake headers with the downtake headers, an upper set of horizontal circulators connecting the separator with the uptake headers, spaced downtake nipples connecting the downtake headers with the water space of the separator, and a set of lower horizontal circulators leading from the uptake headers to the separator and connected to the latter at positions on the separator opposite the discharge ends of the upper circulators, the lower horizontal circulators also extending transversely of the separator at positions below the latter and between said nipples 2. In a cross drum water tube steam boiler, an uptake header structure, a downtake header structure, a bank of horizontally inclined steam generating tubes connecting said header structures, a steam and water separator above said bank of tubes, a first set of horizontal circulators connecting the uptake header structure with said separator and having their inlet ends extending upwardly from the top of the uptake header structure, downtake nipples connecting the water space of the separator with the downtake header structure, and a second set of horizontal circulators connecting the separator and the uptake header structure, the circulators of the second set extending horizontally beneath the separator and communicating with the latter at positions opposite the discharge ends of the circulators of the first set.

3. In a water tube steam boiler having a natural circulation system comprising, in combination, a riser construction, a downtake structure, inclined steam generating tubes connecting the riser construction and the downtake, a steam and water separator, an upper set of horizontal circulators establishing communication between the riser construction and the separator at one side of the latter, and a second set of circulators positioned below the first set and leading from the riser construction to the side of the separator opposite the side to which the circulators of the first set lead, the circulators of the second set extending transversely of the separator at positions below the latter.

LAMBERT KOOISTRA. 

